The subject matter disclosed herein relates generally to commissioning and monitoring of operating conditions for belt-driven applications and, more specifically, to a system for detecting vibration signals using sensors mounted to the electric motor to measure belt tension and to prevent belt failures in belt-driven equipment connected to the electric motor.
Electrical rotating machines, such as electric motors or generators, have become widespread and are found in numerous applications and configurations. Electric machines include a stationary component (i.e., the stator) and a rotating component (i.e., the rotor). In electric motors, a magnetic field is established in the rotor, for example via magnets mounted to the rotor or via an electrical current applied to or induced in a coil wound on the rotor. A second, rotating magnetic field is established as a result of the application of a controlled voltage to the stator, and the rotation of the magnetic field in the stator causes the magnetic field in the rotor to rotate, thereby causing rotation of the rotor. A shaft or other drive member is mounted to the rotor and extends outside the rotor housing providing a mechanical coupling to a device, such as a gearbox, pump, or fan that is to be driven as the rotor rotates. In some applications, the mechanical coupling may be made with a drive belt extending between the drive shaft of the motor and a drive pulley on the belt-driven equipment.
Belt drives may be used in a number of different industrial applications. The belt drive may be, for example, a timing belt, a V-belt, a ribbed belt, an open-ended belt, or an endless belt. The belt drive may be used to transfer power from a motor to a load, provide a direct coupling to a load for limited linear travel applications, or provide an indirect coupling to a load for conveying material in an endless loop. Applications include machine tools, printing, packaging, synchronous conveyors, separators, accumulators, and the like.
During installation, the belt is looped around one or more pulleys to transfer power from the motor to the load. The belt is looped around a drive shaft of the motor, or around a pulley mounted to the drive shaft, and similarly looped around a second pulley or a driven shaft at the belt-driven equipment. One or more additional pulleys or driven members may be included between the motor and the belt-driven equipment to drive additional pieces of equipment, route the belt, change rotation direction, and/or to provide tension in the belt. As the belt is looped around each pulley, the belt may be misaligned either via an offset to one side of the pulley or angularly with respect to the axis of rotation of the pulley on which it is mounted. Further, if tension in the belt-drive system is not properly set, either over or under tension of the belt will be present in the system. Both misalignment and improper tension may lead to excessive wear and/or premature failure of a component in the belt-drive system.
Thus, it would be desirable to detect misalignment, improper tension, or a combination thereof during installation or replacement of a belt in belt-driven equipment.
Due to the rotational nature of an electric machine and the components in the belt-drive system, misalignment and/or improper tension may generate an imbalance in the system due either directly to misalignment or indirectly to excessive wear of components caused by improper tension. During operation of the motor and belt-driven equipment, imbalances can result in vibrations or resonance being generated within the belt-drive system. These vibrations or resonances may not occur throughout the operating range of the motor but may occur at specific operating frequencies. The vibrations may cause excessive wear and/or premature failure of a component in the belt-driven system.
Thus, it would be desirable to monitor operation of drive members in a belt-driven application to detect vibrations present in the system to identify the potential failure of components prior to failure.
In addition to the wear caused by vibration, a shock load applied to the belt-drive system can cause catastrophic failure. If a single shock load does not cause catastrophic failure, it may still cause vibration and/or excessive wear of the belt-drive system. Repeated shock loads may, in turn, result in premature failure.
Thus, it would be desirable to provide a system to monitor operation of drive members in a belt-driven application to detect shock loads occurring in the system.